Lead White

Lead (II) Carbonate (PbCO₃) is a form of lead paint known as white lead. White lead can be made by grinding cerussite, natural lead carbonate, to a fine powder. Most white lead, is however synthesised chemically by reacting metallic lead with acid. It has long been used in art, up until the 1780's, for watercolour and the 20th Century for oils.

Pliny, who called it cerussa, mentioned that its manufacture took place on Rhodes, and was obtained by dissolving lead in vinegar and evaporating to dryness.

Much the same process is described by Theophrastus:

"Lead about the size of a brick is placed in jars over vinegar, and when this acquires a thick mass, which it generally does in ten days, then the jars are opened and a kind of mold is scraped off the lead, and this is done again until it is all used up. The part that is scraped off is ground in a mortar and decanted frequently, and what is finally left at the bottom is white lead.

George Field provides a description of its use:

"In oil painting white lead is essential in the ground, in dead colouring, in the formation of tints of all colours, and in scumbling, either alone or mixed with other pigments. It is also the best local white, when neutralised with ultramarine or black; and it is the true representative of light, when warmed with Naples yellow, or orange vermilion or cadmium, or with a mixture of the yellow and either of the orange pigments, according to the light.
"Ordinary white lead is often mixed with considerable quantities of heavy spar, gypsum, or chalk. These injure it in body and brightness, dispose it to dry more slowly, keep its place less firmly, and discolour the oil with which it is applied, as well as prevent it dissolving completely in boiling dilute potash-ley, a test by which pure white lead may be known."

When white lead is heated, water and carbon dioxide are expelled from the crystal leaving behind the compound lead tetroxide - red lead. All the lead ions are linked with oxide ions, and this chemistry allows them to absorb photons in the green and blue parts of the spectrum, leaving red to be reflected. If white lead is heated gently, however, a different compound, lead monoxide or litharge, is formed. This contains lead and oxide ions, in a ratio and an arrangement; that causes lead the reflection of light at different frequencies. This substance is yellow, and has in the past created another lead based pigment, massicot.

Timeline

512—351 B.C. - An ancient Egyptian cartonnage fragment with polychrome decoration was examined to characterize pigments, binder and construction. The fragment, from a broad collar, was radiocarbon-dated to 512—351 BC. The cartonnage is made on a double layer of plain weave linen, the ground being a mixture of calcite and huntite. The pigment colours employed included white, which was identified as lead white. The Ancient Egyptians, also used lead white in cosmetics.
c. 1523 - Titian mixed lead white with ultramarine to speed up the drying process and hence to prevent cracking of the surface of Bacchus and Ariadne.
c. 1657-1659 - In order to portray the light areas which are necessary to convey the sense of natural illumination, white must be added to heighten most of the darker pigments. Johannes Vermeer (1632-1675), like other contemporary painters, used it extensively to lighten other colours and as the principle component used to depict the characteristic white-washed walls seen in Girl reading a Letter at an Open Window. Vermeer was also aware that the rendering of surface textures enhances the visual significance of various material realities he portrayed.
1821 - White lead has been progressively replaced, first by zinc white, and then by the titanium dioxide pigment discovered in 1821, and first used in oil paints a century later.
1862 - James Whistler used White lead paint for Symphony in White, No. 1: The White Girl.
1909 - France, Belgium and Austria ban white lead interior paint.
2000 - Since the end of 2000 lead-based paints have been banned in the UK. White lead paint is only allowed for use in Grade I and II listed buildings, and then only on the outside.